The lens is known to control its ionic content at concentrations quite different from those of the aqueous humor. It is also known that the anterior lens epithelium can actively "pump" potassium into the lens concomitant with its exclusion of sodium. It is unknown however whether or not the individual lens fibers participate in the active pumping of ions. No specific data exists which proves that fiber membranes can limit movement of solutes, actively pump ions or are able to create P.D.'s across their individual membranes. The objectives of this research are to: 1) determine if individual lens fiber membranes are functionally intact and able to maintain a P.D. across themselves; 2) determine if lens cells function independently of each other or if they are electrically coupled; 3) determine if cells at differnt locations in the lens are functionally similar; 4) determine how bioelectric and diffusional properties of individual lens cells are altered in selected experimental cataracts. These answers will be sought through the use of electrophysiological techniques. These techniques involve iontophoretic and pressure injection of cell markers (Procion dyes and cobalt chloride) into individual lens fibers. The ability of the cells to keep injected substances within their boundaries will be ascertained. An estimate of the membrane resistance of individual fibers will be obtained through the use of double barrel microelectrode techniques. These resistance will be compared to those found in intact cells of other tissues. Cell coupling will be determined through three microelectrode techniques of Loewenstein (30). Induced voltages will be sought in lens cells when current is passed through adjacent cells.